Brake for hoist machinery



Aug. 15, 1944. A. D. PoLsoN BRAKE FOR HOI ST MACIIINFRE Filed May :51, 1943 INVE NQT-O R Alexande v D. P025071.

Abtorncy Patented Aug. 15, 1944 Alexander David Polson, MeWatters, Quebec,

Canada Application May 31, 1943, Serial No. 489,120

2 Claims.

This invention relates to brakes for hoisting machines and particularly for electrically operated mine hoists and winding engines which are equipped with solenoid and drop block emergency brakes. The principal object of the invention is the provision of an auxiliary mechanically electrically operated device to be hereinafter described in detail which, when the power fails, will retard the action of the emergency brake so that the brake bands cannot suddenly act to stop the hoisting apparatus. Sudden stopping of the mechanism causes extreme strain on the cables and attachment links and often causes more or less severe'inpuries to workmen riding in the skips or cages at the time of power failure. My mechanism obviates these mishaps drop block and slowly braking the hoist as in the normal practice of the operator.

The invention also contemplates means, whereby in the event of overwinding, the device can be brought to an almost sudden stop, said means normally being inactive when a sudden stop is not desirable.

My invention may be most suitably adapted to hoisting machinery having a 1500 foot depth capacity actuated at under 900 feet velocity per minute and consists of an air cylinder attached to the auxiliary emergency brake of the hoisting apparatus and arranged'so that the weight which actuates the brakes when a powerfailure' occurs is not permitted to drop suddenly as and for the purpose herein described. The air cylinder is also provided with exhaust valves at the top and bottom and operated by means of an electric solenoid which is in turn controlled by a switch mechanism mounted for actuation upon the depth indicator of the hoisting apparatus and by means of which under certain conditions, the air cylinder will permit the brake to go into instantaneous action.

With the above noted and other objects in view which may appear as the description proceeds the invention resides in the novel construction, combination and arrangement of cooperating parts as hereinafter more specifically set forth, claimed and shown in the accompanying drawing forming part of this application and in which:

Fig. 1 is a side elevational view of the auxiliary emergency brake shown with my air cylinder and component parts attached thereto including the switch mechanism for controlling the solenoid which in turn controls the exhaust valves of the air cylinder.

Fig. 2 is a. longitudinal sectional view of the by retarding the responding parts I causes rotation on air cylinder and exhaust valve, one of which is also shown in section. 7

Referring more in detail to'the drawing in: which similar reference characters designate corthroughout the several views it: will be seen that the invention resides in attachments for an auxiliary emergency brake, gener-i ally designated by the numeral [9, which is attached to the hoisting machinery used in mines and the like. The brake bands H, are caused to frictionally engage the drum l2, in the event of power failure when the solenoid l3 trips lever M," which permits the weight 15 to drop when the post 16, is freed. The dropping of the weight IS, the spindle H, which by means of the coupling member l8, causes the said'fric tional engagement of the bands, on the brake drum l2, all of which is well known to which my invention appertains. 1

Heretofore the sudden dropping of the weight l5, has not been properly arrested with the re sult that a great strain has been placed on the hoisting apparatus when the brakes abruptly and forcefully come into play.

In the preferred embodiment of my invention, I provide a base 29, on which an air cylinder 2L;

having depending lugs 22, is pivotally mounted by means of a spindle 23 disposed through the said base and said lugs. The piston rod 24, isattached, by means of a coupling 25, to the weight bar 25, of the emergency brake ID. A piston 21, provided with suitable air trap piston rings is disposed on the end of the pistonrod which enters the cylinder through a packing joint28, so that an airtight, sliding, weight retaining unit is disposed in supporting arrangement beneath the weight I5. Orifices 29, of predetermined size and number in the bottom of the cylinder 2|, permit the expulsion of air from the said cylinder in controlled volume.

When, upon the failure of power, the weight 15, is released and caused to drop in the manner hereinbefore described, the cylinder 2|, and its component parts retard the heretofore uncontrolled fall of the said weight and thereby permit a gradual tightening of the brake bands on the drum l2, as in the normal practice of the operator. In the manner described above a positive control is attained as the slowly descending piston moves through the cylinder creating a partial vacuum above itself and building up air pressure below itself which is expelled outward through the orifices 29. Thus the bar 26, slowly revolves around the pivot l1., and thereby causes in .the art:

neous action of the emergency brake through the.

medium of the depth indicator. I The cylinder 2|, is provided at top and bottom with outlet ports 30, which communicate by means of pipes 3|, with exhaust valves 32, which are pivotally attached to on a bracket at 34. The rocker arm 33, is actuhereinafter described in detail but it will be seen a rocker arm 33, pivoted l5 ated by an electric solenoid 35, in a manner to be i that when the solenoid is actuated the rocker arm 33,,is rotated around its pivotpoint 34,.thereby drawing each valve stem from its'respective valve seatsolthat the movement of air intoand'out of the cylinder 2| is not restricted or in other words permitting thepiston to descend in the cylinder rapidly, sothat .the emergency brake may: almost instantaneously take effect, v v

- The switch;mechanism-whichactuates the solenoid '35, in the case of overwindingand the like consists of a disk 36,- of sheet iron approxat ly /2 x 43" having three'arcuate slots 31. of 1 20;eac h cut therein which permits the arms 38, to be adjusted to any desired position. The disk;36, is bolted to the gear (not shown) at the back oiathedepth indicator and arranged for rotation therewith. The arms 38, upon due rotation of the disk push againstthe switch box which; is' supported by thebracket llLin a pendue luIn-like manner. The said switch box contains a mercoid tube 4|], mounted in aninclined position on asuitably insulated base terminal block 42, is disposed to connect the flexible leads 43, from the current supply C.

In' operation when the disk '36, revolves the arms 38, which'are disposed in a predetermined position on the said disk push against the pendulum suspendedswitch'box,when a critical position is registered on the depth indicator and in efiect throw the switchbox off its normal, vertical position thereby permittingthe mercury in the tube 40, to flow from terminal to terminal to complete the electrical connection-wherebythe sole- 4|, upon which the changes in .be resorted to within From the foregoing it will be seen that the mechanical electric device when correctly mounted upon the hoist apparatus will efiectively overcome the danger of sudden stopping and straining of cables, distortion of cages, etc., whilst permitting sudden stopping under certain critical circumstances when such sudden stopping is unavoidable.

. It is believed that the construction and advantages of the structure shown may be apparent from the foregoing paragraphs taken in conjunction with the accompanying drawing without further detailed description.

"While the preferred embodiment of the invention has been disclosed it is understood that minor the details of construction, combination and arrangement of cooperating parts may the scope of what is claimed Without departing from the spirit of the invention.

I claim: I

1. Braking apparatus for hoisting machinery having a depth indicator adapted to be attached to dropblock emergency brakes and consisting 'of an air cylinder, a piston slidable in the cylinw 'der, a piston rod attached -to the weight bar of the drop block emergency brake; exhaust valves at the top and bottom of the cylinder, said valves being normally closed, a rocker arm attached to the valve stem of each valve, said rocker arm being actuated by a solenoid, means to actuate the solenoid from the depth indicator of the hoisting apparatus.

2. Braking apparatus for hoisting machinery having'a depth indicator adapted to be attached to drop block emergency'brakes and consisting of an air cylinder, a piston slidable in the cylinder, a piston rod attached to the weight bar of the drop block emergency brake, exhaust valves at the top and bottom of the cylinder, said valves being normally closed, a rocker arm attached to valve stem of each valve, said rocker arm being actuated by a solenoid to open the exhaust valves, means to actuatethe solenoid from the depth indicator of the hoisting apparatus including a pivotally mounted mercoid switch for controlling the solenoid circuit; a disk attached to the depth indicator, adjustable arms on the said disk arranged to push against the mercoid switch and tilt same at certain predetermined positions of the said depth'indicator thereby causing the mercoid switch to closeand complete the circuit to the solenoid.

ALEXANDER DAVID POLSON 

